1. Field of the Invention
The present invention relates to a method and apparatus for digitally recording and reproducing a color video signal, particularly for a SECAM television system.
2. Description of the Prior Art
In digitally recording and reproducing a color video signal for a NTSC or
television system in the state of a composite signal, a horizontal synchronizing signal and a burst signal both included in a horizontal blanking interval as shown FIG. 4, are not recorded. Only the signal within a scanning interval is digitized and recorded. In the reproducing mode, the horizontal synchronizing signal and the burst signal obtained from the reproducing unit are added to the signal. This technique reduces the amount of information to be recorded. Such technique is based on the fact that, in the color video signal for a NTSC or PAL system, if the horizontal blanking interval is cut out from the color video signal, it can be restored with ease since the cutout point thereof is at the pedestal level which is maintained constant as shown in FIG. 4.
On the other hand, in the color video signal for a SECAM system, the non-modulated carrier corresponds to the burst signal portion in the composite NTSC or PAL signal, as shown in FIG. 5. The non-modulated carrier is continuous with the video portion in the scanning interval as shown and, in addition, its phase is not exactly kept fixed to the sampling axis for digitization.
Therefore, if the horizontal blanking interval, which includes the horizontal synchronizing signal and the non-modulated carrier, is cut out when the SECAM signal is digitally recorded, it is difficult to restore the non-modulated carrier portion in the reproducing mode. Thus, it has been customary heretofore to also record the non-modulated carrier also in digital recording and reproduction of the SECAM signal.
In recording the SECAM signal according to the prior art, since the non-modulated carrier is also recorded, there is no reduction in the amount of information to be recorded. Furthermore, it has been impossible to achieve compatibility with a digital VTR designed for a PAL color signal of the same line sequential video system.